URL Encoder/Decoder

URL encoding (also called percent-encoding) is the process of converting characters into a format that can be safely transmitted over the internet in URLs. Since URLs can only contain a limited set of characters — specifically unreserved characters (A-Z, a-z, 0-9, hyphen, underscore, period, and tilde) — any other character, including spaces, punctuation, and non-ASCII text, must be replaced with a percent sign (%) followed by its two-digit hexadecimal ASCII code. So a space becomes %20, an exclamation mark becomes %21, and the & symbol becomes %26.

Without URL encoding, special characters in URLs would be misinterpreted. A space would break the URL, a question mark would signal the start of query parameters, and an ampersand would separate parameters when it was intended as literal text. URL encoding ensures that every character arrives at the server exactly as you intended it, which is essential for form submissions, REST API calls, and any link containing special characters, emojis, or non-English text.

This converter handles both encoding and decoding, using the standard JavaScript encodeURIComponent (for full URL component encoding including query string values) and encodeURI (for encoding entire URLs while preserving structure like slashes and query delimiters).

URL encoding replaces each disallowed character with a percent sign followed by its two-digit hexadecimal byte value in UTF-8. For ASCII characters, the hex byte matches the ASCII code point. For non-ASCII characters like emojis or Chinese text, the UTF-8 byte sequence is encoded as multiple percent-hex groups.

This converter provides two encoding levels: encodeURIComponent encodes everything including slashes, making it suitable for individual query parameter values and form data, while encodeURI preserves URL structure (colons, slashes, question marks) and is suitable for encoding complete URLs that already have a valid structure.

JavaScript provides two encoding functions, and choosing the wrong one is a common source of bugs. encodeURIComponent is the safer choice for most purposes — it encodes every character that is not a letter, digit, or one of the safe characters (-_.!~*'()). This means slashes, colons, question marks, ampersands, and equals signs are all converted to their percent-encoded forms. Use encodeURIComponent when encoding individual values in a query string, form fields in a POST request body, or path segments that may contain special characters.

encodeURI is more conservative — it preserves the characters that have syntactic meaning in a complete URL: colon (:), forward slash (/), question mark (?), ampersand (&), equals sign (=), and hash (#). Use encodeURI only when you have a full URL that may contain non-ASCII characters in the path or query string but whose structure is already valid. Encoding individual parameters with encodeURI can leave special characters unencoded, leading to broken URLs. This converter shows both results, letting you see the difference and choose the right encoding for your use case.

The converter operates in two modes selectable from the top buttons:

1. Encode mode: Enter any text — a search query, form value, filename with spaces, or string containing emojis or international characters. The converter produces the percent-encoded version suitable for URL query strings, plus a variant using encodeURI for full URLs. Click the Copy button to copy the result to your clipboard.
2. Decode mode: Paste a percent-encoded string like "Hello%20World%21" and the converter restores the original text. This is useful for reading encoded URLs from server logs, debugging API responses, or understanding what raw data a form submission contains.

The common encodings reference grid at the bottom shows 12 frequently encountered percent-encoded characters with their raw symbols for quick lookup without typing.

URL encoding is essential in several common scenarios. When submitting HTML forms using the GET method, the browser automatically URL-encodes the form field values before appending them to the URL as query parameters. When building REST API URLs programmatically, you must manually encode query parameter values — forgetting to encode a value like "John & Jane" results in "John%20%26%20Jane" on the properly encoded request.

When constructing URLs that contain user-generated content — search terms, usernames, filenames, or free-text descriptions — URL encoding prevents injection attacks and malformed requests. Spaces, quotes, angle brackets, and non-ASCII characters in user input must all be encoded before the URL is sent. When working with redirect URLs in OAuth flows, the redirect URI itself must be URL-encoded when passed as a query parameter, resulting in double-encoding that this converter can help you debug.

For international text and emojis in URLs, encoding is mandatory. The emoji 😊 (U+1F60A) encodes to %F0%9F%98%8A — four hex bytes representing the UTF-8 encoding of the code point. Modern browsers display the decoded emoji in the address bar, but the actual HTTP request contains the percent-encoded form, and this converter lets you see both representations side by side.